With the progress of recent electronics technology, the reduction in size and the increase in capacitance have been required for laminated ceramic capacitors. In order to satisfy these requirements, the reduction in layer thickness has been advanced for dielectric layers of laminated ceramic capacitors. However, the reduction of the dielectric layers in layer thickness relatively increases the electric field intensity applied per layer. Therefore, improvements in reliability in the case of applying a voltage, in particular, improvements in lifetime characteristics in a moisture resistance loading test have been required for the dielectric ceramic for use in the dielectric layers.
For example, Patent Document 1 discloses a dielectric ceramic containing a main composition represented by [(CaxSr1−x)O]m[(TiyZr1−y)O2] as a main constituent where the values of x, y, and m respectively fall within the ranges of 0≦x≦1, 0≦y≦0.10, 0.75≦m≦1.04, and containing, as accessory constituents for the main constituent, 0.2 to 5 mol % of Mn oxide in terms of MnO, 0.1 to 10 mol % of Al oxide in terms of Al2O3, and 0.5 to 15 mol % of constituent represented by [(BazCa1−z)O]vSiO2 where Z and V respectively fall within the ranges of 0≦Z≦1 and 0.5≦V≦4.0. Further, the accelerated test carried out at a high temperature and under a direct electric field concludes that a dielectric ceramic is achieved which has insulation resistance for a long accelerated lifetime.
Patent Document 1: Japanese Patent Application Laid-Open No. 10-335169